Last week, a mind-boggling sheep puzzle went viral. Counting sheep is supposedly an ideal way to fall asleep, but this field of woolly creatures is bound to do the exact opposite.

A new Where's Wally? style puzzle challenges you to find the one sheep in the flock that's drifted off to sleep. The puzzle, created by Drift Sleep, has an added challenge as there's a sheep dog watching over the flock for you to also spot.